0b083e3d8c
Previously, all GVariants would allocate a GBytes for the buffered contents. This presents a challenge for small GVariant type created during the building process of GVariantBuilder as that results in an allocation for the GVariant, GBytes, and the byte buffer. Recent changes for GBytes may reduce those 3 allocations to 2, but even that is quite substantial overhead for a 32-bit integer. This changeset switches GVariant to use g_new/g_free allocators instead of g_slice_new/free. When benchmarked alone, this presented no measurable difference in overhead with the standard glibc allocator. With that change in place, allocations may then become variable in size to contain small allocations at the end of the GVariant reducing things to a single allocation (plus the GVariantTypeInfo reference). The size of GVariant is already 1 cacheline @ 64-bytes on x86_64. This uses that to guarantee our alignment of data maintains the 8-bytes guarantee of GVariant, and also extends it to match malloc(). On 32-bit systems, we are similarly aligned but reduce the amount we will inline to 32 bytes so we have a total of 1 cacheline. This is all asserted at compile-time to enforce the guarantee. In the end, this changeset reduces the wallclock time of building many GVariant in a loop using GVariantBuilder by 10% beyond the 10% already gained through GBytes doing the same thing.
GLib
GLib is the low-level core library that forms the basis for projects such as GTK and GNOME. It provides data structure handling for C, portability wrappers, and interfaces for such runtime functionality as an event loop, threads, dynamic loading, and an object system.
The official download locations are: https://download.gnome.org/sources/glib
The official web site is: https://www.gtk.org/
Installation
See the file ‘INSTALL.md’. There is separate and more in-depth documentation for building GLib on Windows.
Supported versions
Upstream GLib only supports the most recent stable release series, the previous stable release series, and the current development release series. All older versions are not supported upstream and may contain bugs, some of which may be exploitable security vulnerabilities.
See SECURITY.md for more details.
Documentation
API documentation is available online for GLib for the:
Discussion
If you have a question about how to use GLib, seek help on GNOME’s Discourse
instance. Alternatively, ask a question
on StackOverflow and tag it glib.
Reporting bugs
Bugs should be reported to the GNOME issue tracking system. You will need to create an account for yourself. You may also submit bugs by e-mail (without an account) by e-mailing incoming+gnome-glib-658-issue-@gitlab.gnome.org, but this will give you a degraded experience.
Bugs are for reporting problems in GLib itself, not for asking questions about how to use it. To ask questions, use one of our discussion forums.
In bug reports please include:
- Information about your system. For instance:
- What operating system and version
- For Linux, what version of the C library
- And anything else you think is relevant.
- How to reproduce the bug.
- If you can reproduce it with one of the test programs that are built
in the
tests/subdirectory, that will be most convenient. Otherwise, please include a short test program that exhibits the behavior. As a last resort, you can also provide a pointer to a larger piece of software that can be downloaded.
- If you can reproduce it with one of the test programs that are built
in the
- If the bug was a crash, the exact text that was printed out when the crash occurred.
- Further information such as stack traces may be useful, but is not necessary.
Contributing to GLib
Please follow the contribution guide to know how to start contributing to GLib.
Patches should be submitted as merge requests to gitlab.gnome.org. Note that you will need to be logged in to the site to use this page. If the patch fixes an existing issue, please refer to the issue in your commit message with the following notation (for issue 123):
Closes: #123
Otherwise, create a new merge request that introduces the change. Filing a separate issue is not required.